错误:在非对象上调用成员函数 format(） 生成一年中的每一天

我有一个日历类，我在其中仅从用户输入年份并生成一年中的一整天并保存在数据库中。

class Calendar
{
   /**
     * @var 'DateTime
     *
     * @ORM'Column(name="today_date", type="datetime", nullable=true)
     */
    protected $todayDate;
    /**
     * @var boolean $isBusinessDay
     * @ORM'Column(name="is_business_day", type="boolean", nullable=true)
     */
    protected $isBusinessDay;
    /**
     * @var boolean $isHoliday
     * @ORM'Column(name="is_holiday", type="boolean", nullable=true)
     */
    protected $isHoliday;
    /**
     * @var time $openTime
     *
     * @ORM'Column(name="open_time", type="time", nullable=true)
     */
    protected $openTime;
    /**
     * @var time $openTime
     *
     * @ORM'Column(name="close_time", type="time", nullable=true)
     */
    protected $closeTime;
}
if ($form->isSubmitted() && $form->isValid()) { 
  $weekday = $form["weekday"]->getData();
  $start_date = $form["todayDate"]->getData();
  $start_date = (string) $start_date->format('Y-m-d');
  $start_day = date('z', strtotime($start_date));
  $days_in_a_year = date('z', strtotime('2016-12-31'));  
  $number_of_days = ($days_in_a_year - $start_day) +1 ;
  for ($i = 0; $i < $number_of_days; $i++) {
      $date = strtotime(date("Y-m-d", strtotime($start_date)) . " +$i day");
      print date('d F - l', $date) .'<br />';
      if (in_array(date('l', $date), $weekday))
      {
        print "Match found".'<br />';
        $date_temp2 = date('Y-m-d',$date);
        print $date_temp2.'<br />';
        $date_temp = new 'DateTime($date_temp2);
        $TodayDate = $date_temp->format('Y-m-d');
        $calendar2 = new Calendar();
        $calendar2->setTodayDate($TodayDate);
        $calendar2->setOpenTime($form["openTime"]->getData());
        $calendar2->setCloseTime($form["closeTime"]->getData());
        $calendar2->setIsBusinessDay(true);
        $calendar2->setIsHoliday(false);
        $em->persist($calendar2);
      }
      else
      {
        print "Match not found".'<br />';
        $calendar2 = new Calendar();
        $calendar2->setIsBusinessDay(false);
        $calendar2->setIsHoliday(true);
        $em->persist($calendar2);
       }
      }
    $em->flush(); 
   }

实际上，我只想从用户那里获得年份。获取一年的第一天并存储在数据库中，添加一个增量日。在"如果阻止"中，它打印全年的日期。自

30 December - Friday
Match found
2016-12-30
31 December - Saturday
Match not found

最后我收到此错误

错误：调用非对象上的成员函数 format（）